Method of hobbing tapered gears



Aug 12, 1930. A. H. CANDEE 1,772,585

METHOD 0F IOBBING TAPERED GEARS Filed April 9, 1928 @prayed M 30 45 l INVENToR gangli am mrfgvrably from Patented Aug; .l ,l

' f The present' invention -rlatestofemetlicd cfA 1 1 ')blo'in`,vV tperedgearS `and! especially yto` a niethofdfef gerieratingj'spiral f bevejelfg esi-rs` irl a;

, 5 Gegrs -of thelcha'racter describedfas hobbed acccrdingrto erfhobbingftgpeised"gears "i l" i f BGHESVTERI MWYORK, lfwRromilcNoF kNEW YORK #Si previous processes, h "avelllackedf` process;

, ig'earjqaceordin p b eY'eLgearS fili which y 1,928'. y Serial No. zes'sss;

jing

Withfa mate gear,

"vIligth'edrawings:

.qlligres" landk .ere a "Plainview4 andarlj end#4 Y el'evatlon; f respectlvely, alluetrartirlg dmgra mtca11yfthemethod heretofore femplyed ci ge'eratinf bevelfge'ar'blank urngf the generati'orrffl al Altok rone' 11 process heretcfore f' inifentin; arid Spiral bevel gear w @61m11- wringiwhich mismatch eaeli other lengthwise @The present` `invention is particularly applicable t'fthe'fgelieration pfspirgl kbevel t gears'with alk t'afpflfecl`` hob of cnstant pitch in axial'section Employingfthe present inventi in generat-v gears 'with a 4hob `ithis type, instead oft` prclucing -f ak gear ha'lving teeth Tand? toth generated'` byy membersof a'pair A -gatezin the pitch plane 13 or 22 of the basic Ver j blank about t crown gear at Arespective apexes.

Y mnltaneous y movement Y1s two wl lack adjustment inimesh. Y

- gear being hob i-ating gear surface 13; that is, its pitch cone angle is 90.

To generate' the gear vv11, the hob 10 is so positioned relative to the blank as to repret sent the imaginary crown gear 12, its pitch surface `bengta'n ent to the pitch p1ane13A i blank arerotated continuously in mesh about of this imaginary asic generatingge'ar, and

the position of its apex 19 and the otset of its axis 14 from the axis 15 of the basic generatin gear being determined by the struc-t is ture o the hob and basicgenerating gear, as weil known'inthe art. The bevel gear blank ltris, positioned so'that its axis 17 intersects the axis 15 of the imaginarygenerating crown geah12 in` the blank apex 18. With the hob lrand gear blank 11 in engagement, the hob andy-.blank will ber rotated continuously on their respective axes 14 and 17 and simu1ta A nennst] a continuous relative rolli tion ywillbe Eroduced between the ho ,and eaxis 15 of the imaginary genexisting.. crown gear 12,'thereby to generate toothsurfaces-on the blank conjugate to thev imagini' y generatin crown ear. 'Flgurg2 shows gne application of this process to the generation of a spiral bevel v n2() withaltaper. hob 21 of constant axial pitch `The pitch plane of the imagina? basic 'generatingcrowngear lre resentedj y the oblis designated atr22 any 1 he 23. 24fatrlic) 25 gesignatg-s spective "'tj ,axeso o `an arf 'a' while26 and 27 desi nate, respeclelyytheir the generation `of the hob 21 and blank 20 are rotated gmrfo, the

on their respective axes-.midsicontinuousl reducedv between the hob .and blank 'about t e axis 23 of the basic crown gear'represented b the ho y According to previous met ods, both memb'ersof a pair of spiral bevel gearswill be the same process. The two hence are exactly conjugenerating crown gear and the'teeth of the ars will match each other exactly along their full length.A

Alliiguresi and 5 illustrate themethodof` bobbing according to the present invention.;- Here onek or both memberslof the pairfis by rolling `a hob and a gear on are generated t to each other as'v though the blank :relativelhaving a conicalgiitch sur-l tht isga pitch coneangle 'o less than .y "a The hob; which maybe of the Vsame constructibnias the liobsemployed in any; ofrilte g 'fis so adjusted-relative to-theage@ blank viousv promesas',4 is indicated at 30.r

`32 represented by the V.the axis of` `this f the .taub-will eontect. withr surface 32 of,v the generating gear zal .an a.

a. continuous relative rolling nerat- Y For this reason, the gears f Y ofteg'earblank d' were meshing with a basic ends tween; the?A mating 31 that it represents an imaginary conical generating gear 32. The pitch surfaces of the blank and of the basic generating vgear 32 represented by the hob 30 will be tangent to the plane 33 when the hob has been fed into full depth. t The axis of the` imaginary basic generating -gear,.which is axisof the cradle in a mac ine for practising this linvention is designated at 34. For generating theteeth of thegearythe hob and their respective axes 35 and 36 and simultaneously a continuous'relative rollin movement produced between the hob and lank about the axis 34 of the imaglinkary generating gear Figure 6 shows onfa large scale,- alta'perhob of constant itch suchas ma ,be em leyedin practising t is invention. his ho maybd otthesame constructionas the hob.; 21 rof 'Elfi `here the hob represents, asillnstmtedin Figs. M03, a basic generating gear met, plane 'tch surface, the pitch surface ofthe hob. will be tangent tothe `pitch plane of the generating crown and during the ro ,li

ear. along a, straight line motion between,V lthe hob and'blank, the teet .of the blankwill be cut to their full depth. When both embers of agpairfof gears are enerated in s fashion, their matingI toot surfaces will match each other` as alreaclstateexactly alon theirwhole 1ength...;f eine,however,as wit the present invention, conical 'generatin'gfgear, ythe .ptc rcome 9K; the .conctsh point; as illustrat in Figs.' 4, 5 and `.since theaxes of the' ptclrlfarie` 0f tha-hebimdthe gmlxatin gear, are not in the same plane. `n' both 'rectionsaway Vfrom the point rof tangeno the hob will `extend the ,pito surface 32. of the eneratin'ggear and, so will eutjto a greater;H pth- .Thomas clearly shown. inV Figf 6e. the teeth 41va11d42 towards .the twotends' of t. hebV cuhplsgaes: sivelyfd Mr than. the too h 4:3r locati-2dcen` trallyioft eilengthof the hob.; .f. `.Since theteeth of the hob increasein width from thirmttr-ends totheir roo aswill be `eeenlinlFg...16, it will be ucl ar 1that ,with the recess of the resent'invenetion the 1teeth thinner at their ends :th The Aolfattof this Ais.fillustrated in 7.

Thisktoeti is thinner at -itsouterimd'itainner ends than at" its center andthe grooves of the gear willlia correspondingly widmet their .than atfther nenterav .v'lhe` matetgear niayVbe-'genarate-aeeoading to4 methods heref totonefem loyedon iaothe `same;.taaiieuma the geen w Ine'ither event theeontmt ber mgf'fmg Wm the hob re rasantes ning' generated ,will-'be cut anat theirfeenters.

re resentedby the lli.

further beyond 3* v navman producing a relative rolling movement between the hob and blankcorresponding to that of a gearri'olling with a conical generat-V iaxg'gearV oiother than 90QV cone an le while maintaining the apexof the blank o set from the :axis of the basic generating gear.

8. The method of producing a pair of tap? eredk gearsA which consists in cutting each member of the pair by positioning a worm hob and a tapered gear blank in engagement, with the axis of the hob angularly disposed to and oset from theaxis of the blank, rotating` the hob andblank continuouslyin engage/ment and simultaneously producin a relative rolling movementl between the `ob and blank corresponding to lthat of a gear rolling With aV conical generating gear of vfrom the axis of the blan and blank `continuously infengagementand other than 90 pitch cone angle.

9 The method of producing dagear blank in engagement,'with the axis ofthe hob angularly dispiosed to and :offset rotating the heb simultaneously producingA a relative rolling movement between the hob and blankcorreyspending to that of agearrolling with a conical generating vgear of other than 90o pitch coneau le. 1 i

n .10. ered lgearsv which consists lin cutting each member of the parlby `positioning Va taper heb of constant axial pitch and a gearblank inengagemennwith the axis of the hob angu Y larly disposed to `and offset from'the axisof` the blank, rotating the `hob and blank cntinuously in engagement and simultaneously proi ducin a relativerolling movement between s the ho and blank corresponding to that of a a gear rolling with a-conicalgenerating gear of other than 90 itch cone angle.

.11. The meth" 'ofi generating abevel gear( i l by means of a hob having itscuttingteeth arfin a helical' thread whichcnsists in 'Y ran ppsitoning and moving' the hob and gear Vheb to representan imaginary generating gear having a pitch cone angle of slightlyless v i than 90 `and generate tooth surfaces on the e blank conjugatetosuch imaginary generating geen@ rf Y n v y ALLANH-CANDE-E.

a pair of tap- Vered gears which .consists in` cutting each memberof the pair by positioning a taper hobl u? 1 e method oiiproducing alpair of tap 1 ank relatively to `each other as to Vcause the 

